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A weekend heat wave has hit the Bay Area Sunday, with triple digit heat sweltering some parts--including one East Bay city. NBC Bay Area's Monte Francis reports from Walnut Creek where people are trying to beat the heat. (Published Sunday, June 8, 2014)

A weekend heat wave has hit the Bay Area Sunday, with triple digit heat sweltering some parts.

Highs were expected to be in the upper 60s to the lower 80s, and over 100 in some parts of the Bay Area Sunday, with southwesterly winds of up to 10 mph.

Walnut Creek is one city seeing triple digit temperatures. Throughout Sunday, the temperature has been reading 100, or close to it.

Usually on a weekend in June, lots of people would be outside enjoying the mild weather in this East Bay city. But on Sunday, it appeared most people were staying out of the heat.

Sunday Sizzle Inland

High pressure will strengthen over Northern California to wrap up the weekend leading to temps climbing well into the 90s to near 100 inland across our valleys near the Delta, Tri-Valley and South Bay.Closer to the coast a moderate sea breeze and marine layer in the 500-1000 ft. range should keep the heat confined mainly in inland areas. Highs near San Francisco will be in the mid 70s to lower 80s with mid 80s for Oakland. San Jose south should see highs in the lower 90s to near 100. Sunday is also a Spare the Air day with the worst ground level ozone concentrations in the East Bay and Santa Clara valleys.Monday should be nearly as hot inland as a stronger sea breeze begins to develop by mid-afternoon. This will lead us into more significant inland cooling as a trough of low pressure to our north promotes more onshore, cooling winds through the middle and latter half of the week.Rob Mayeda

The outdoor seating at Walnut Creek cafes were empty in the afternoon, and people were cooling off by staying in air-conditioned spaces--like a local gelato shop.

"It’s really hot outside, over 100, so we decided on having gelato," Nanette Hong of Danville said.

The owner of the shop said he is twice as busy as he had been on a regular Sunday.

Sunday was also declared a Spare the Air Day, which means high temperatures and low winds are making for unhealthy levels of smog in the air. The public is urged to avoid exercising outdoors, especially at the hottest time of the day.

Air quality officials have declared another Spare the Air Day for Monday.

That means there is a ban on wood burning, and people are asked to carpool or take public transit to work to cut down on the levels of exhaust in the air. And it also means people who are sensitive to smog should limit their time outdoors

And for those who must be outside, they should have plenty of water on hand, air quality officials said.